Mozart completed this work on December 4, 1786, and very likely premiered it the following night in Johann Trattner's Viennese Casino. It is scored for single flute, two each of oboes, bassoons, horns, and trumpets, strings, and solo keyboard, of course.
This last of Mozart's four C major piano concertos is a work of immense structural integrity (rather than cultivated thematic charm), employing alternations between parallel major and minor keys throughout. It is furthermore a work whose three movements use sonata-form: pristinely so in the first; without a development section in the second, and as part of a seven-part rondo format in the last (i.e., the development of materials introduced during the first refrain in couplets B and C). Concerto No. 25 and the "Prague" Symphony (D major, K. 504) were composed conjunctively -- Mozart wrote December 4 and 6, 1786, as their completion dates in his Verzeichnis -- for a series of four Advent Akademien in the Casino of his friend Johann Trattner. Evidence suggests that he repeated the concerto on several subsequent occasions, and that Beethoven chose it in 1795 for one of his first Viennese appearances as soloist.
"Magisterial" befits the main thrust of the opening Allegro maestoso, the longest movement in Mozart's orchestral canon: 432 measures without cadenza (which surely would have extended it). The outset of his double exposition is built on a C major triad, although subsequent materials and their treatment contain passages of expressive intimacy, not to be confused with softness or effeminacy. As if by Schubert, the music slips in and out of minor keys (always the opposite of prevailing major-keys). The music recalls pensive moments from Figaro when it is not being assertively symphonic -- as if Mozart were getting ready for the "Jupiter" Symphony of 1788.
For the middle movement, a generic Andante tempo marking belies the depth and variety of fantasy in this F major sonatina in triple time. Again, the orchestra plays an exposition with two theme groups before the piano enters, a highly decorated part that doesn't need further embroidery. The prevailing mood is pensive without solemnity; Mozart was too professional by this time to be caught out.
While the manuscript had no tempo marking for the final C major sonata-rondo in 6/8 time, Allegretto has been the consensus ever since Mozart's widow published K. 503 in 1789 (her only venture into business and a failure). The refrain-theme begins with eight measures of gavotte from the ballet music in Idomeneo -- the opera seria Mozart composed six years earlier, at Munich. Although Erik Smith considers this movement "festive," Cuthbert Girdlestone ranks it among the "most serious-minded rondos, [having] nothing of the merry tone of the usual rondo." The first theme is "tinted with melancholy, serious, almost brooding...full of a languishing grace unexpected in a concerto finale." Major-minor mood swings carry over from the first movement until, in couplet-B, "intensity reaches passion." It is "an epiphany" for Michael Steinberg when "the piano, accompanied by cellos and basses alone, a sound that occurs nowhere else in Mozart, [leads to] music whose richness of texture, poignancy and passion astonish us." However, sunlight pours illuminates the final refrain.